The formation of a polycrystalline 3D gallium-imidazole framework (MOF) was closely studied in three steps using ssNMR, XRPD, and TGA. In all steps, the reaction products show relatively high temperature stability up to 500 degrees C. The final product was examined by structural analysis using NMR crystallography combined with TG and BET analyses, which enabled a detailed characterization of the polycrystalline MOF system on the atomic-resolution level. Ga-71 ssNMR spectra provided valuable structural information on the coexistence of several distinct gallium species, including a tunable liquid phase. Moreover, using an NMR crystallography approach, two structurally asymmetric units of Ga(Im(6))(6-) incorporated into the thermally stable polycrystalline 3D matrix were identified. Prepared polycrystalline MOF material with polymorphic gallium species is promising for use in catalytic processes.